xml文件中的内容，（）是正确的？
A.<?xml version="1.0" encoding="gbk" standalone="no"?> <root></root><id>1</id>
B.<?xml version="1.0" encoding="gbk" standalone="no" ?> <root><id>1</id></root>
C.<xml version="1.0" encoding="gbk" standalone="no" > <root></root><id>1</id>
D.<xml version="1.0" encoding="gbk" standalone="no" > <root><id>1</id></root>
正确答案是B